Effect of Yb3+ concentration on upconversion luminescence of AlON:Er3+ phosphors

AlON:1.6 mol.%Er3+, x mol.%Yb3+(x=0, 2.6, 3.1, 3.6, 4.1, 4.6) phosphors were synthesized successfully by aluminothermic reduction and nitridation(ATRN) method and characterized by X-ray diffraction(XRD), scanning electron microscopy(FESEM) and upconversion photoluminescence(UCPL) emission spectra. Under the excitation of diode laser 980 nm, the green(556 nm) and red(655 nm) upconverted emissions were observed, attributed to the 4S3/2→4I15/2 and 4F9/2→4I15/2 transition of Er3+respectively. The emission intensity increased with increasing Yb3+ concentration due to the energy transfer(ET) between Yb3+ and Er3+. The upconverted emission reached the highest as x=3.6, and was pump-power dependent involving a two-photon process.